Security booklets, such as travel documents (e.g. passports), typically comprise multiple pages which are bound together along an edge of the booklet (for example, by sewing sheets together down the middle and then folding them at the sewing line) one such page typically being a machine-readable information sheet in accordance with ICAO (International Civil Aviation Organization) specifications and comprising various printed security features, a photograph and other personal information identifying the document holder. More recently, this information sheet, or another information sheet of the security booklet, may comprise an embedded contactless integrated circuit chip and antenna which form part of a security system designed to enhance the level of security associated with the travel document. Similarly, another information sheet of the security booklet could be used as a carrier for other high capacity electronic storage media such as contact-based integrated circuit chips, magnetic strips and optical memories.
Depending on the function and composition of the information sheet it may be necessary, or desirable, that it be made of a hard and durable synthetic material differing substantially in character from the remaining pages of the booklet which, typically, are comprised of a soft and pliable paper that can be sewn together and withstand repetitive bending and flexing at the bound edge. This is because of certain improved security measures which may now be applied to the personification of such security booklets, such as the use of laser engraving and/or the use of a contactless integrated circuit chip and antenna embedded within the information sheet itself. These improved security measures require that such an information sheet be hard, durable and thicker than the accompanying paper sheets with which it must be bound and, in turn, the harder, thicker character of such information sheet presents a problem as to how to durably and securely bind them within the booklet.
This problem arises because a hard, durable sheet material cannot be satisfactorily bound, at one of its edges, with pliable sheets, so as to form part of a travel document such as a passport. Such materials are too hard for the sewing process and cannot be folded as needed for the sewing/binding process. Moreover, a hard material fixed into the binding would not be able to withstand the normal, day-to-day, flexing and bending that travel documents may be subjected to over the term of their use.
To overcome this problem, it is necessary to find a method of securely binding a hard, durable sheet, capable of functioning as an information sheet, to a flexible band that can be effectively bound into a booklet and provide the required flexibility and durability, for usage, at the binding edge. If like materials are selected for the durable sheet and flexible binding edge portion, these can be laminated together to form the desired construction having such a flexible edge piece for binding into a booklet, an example of such a construction being European Patent Application No. EP 1,245,407 of Setec Oy published on 27 Mar. 2002. However, where dissimilar materials are desired for the durable sheet and the binding edge, lamination may not provide an acceptable option since dissimilar materials may not effectively laminate to each other.
U.S. Pat. No. 6,213,702 to Wesselink, issued 10 Apr. 2001, discloses a possible solution to such problem posed by dissimilar materials, whereby a flexible band is affixed to a finished synthetic, hard sheet, referred to as a plate, by means of a separate joining strip positioned over the band. The joining strip is configured with projections to mechanically fit into mating perforations formed along the edge of the flexible band which is positioned over the hard sheet, such that the only direct connection made is between the joining strip and the plate, the connecting surfaces being the bottom surfaces of the projections and the top surfaces of the plate exposed by the perforations in the band. Those connecting surfaces of the separate joining strip and the plate are affixed by means of either a mechanical clamping fit between the projections and perforations or by fusing them together (i.e. by melting them together by ultrasonic welding if the material used for the joining strip is the same as that of the plate). However that possible solution has the disadvantage of requiring use of a separate joining strip.
European Patent Application No. EP 1,380,442 of Setec Oy, published on 14 Jan. 2004, and U.S. Pat. No. 6,135,503 to Lob et al., issued on 24 Oct. 2000, each disclose an identification document comprising a durable data sheet with a more flexible edge for binding with additional booklet sheets, whereby the durable sheet is formed by laminating plastic layers together in the data area of those sheets but preventing such lamination from occurring at the edges of those sheets by providing intermediary separation layers between them in only that edge area. Thus, these methods require the step of specifically positioning such intermediary separation layers in the edge area.
Accordingly, there remains a need for means to securely couple together dissimilar first and second materials, one being a hard, core material and the other being a flexible material suitable to be bound with paper sheets by sewing them together, without any need for a separate joining component or separate separation layers.